As will be understood by those skilled in this art, pierce nuts are typically installed in a metal plate or panel by an installation apparatus including an installation head generally attached to the upper die platen or shoe of a reciprocating die press and a die member or die button installed in the lower die shoe or die platen, wherein the panel is fixed to the lower die shoe or die platen overlying the die button. Pierce nuts are fed to the installation head opposite a reciprocating plunger which, upon closing of the die press, drives the pierce nut into the panel, piercing a slug from the panel, and the die button then installs the pierce nut in the pierced panel opening. The slug pierced from the panel is then received in an opening in the die button, which typically retains several slugs before ejecting the slugs. The panel may be simultaneously formed by the die press and several pierce nuts may be simultaneously installed in the panel with each stroke of the die press, particularly in mass production applications. On occasion, through misalignment, improper die press setting or improper nut installation, the panel slug may remain attached or partially attached to the panel causing potential quality issues during the assembly operation, wherein the panel having the pierce nut attached is assembled to a second component. In the automotive industry, for example, the assembly operation is typically carried out at a different location. Another problem associated with the installation of pierce nuts is the stacking of the panel slugs in the die button opening. The stack of slugs may “cold weld” together, forming a barrier to the entrance of further slugs and resulting in a poor or partial installation of the pierce nuts or requiring greater force to push out the slugs. It is not always possible to visually inspect the opening through the die button, particularly in time to shut down the die press to avoid improper installation of further pierce nuts by the installation apparatus. Further, the improper installation of the pierce nuts described above may not be discovered until later in the assembly process.
It would therefore be very desirable to continuously monitor the pierce nut installations during the installation of the pierce nuts and simultaneously monitor the slugs pierced from the panel during installation. However, the prior art does not disclose an apparatus or method capable of continuously monitoring these problems and potential problems with the installation of pierce nuts.